@article{zhong_kirmani_lan_carpenter_rong-hui chew_awartani_yu_niazi_voznyy_hu_et al._2022, title={Conjugated polymers with controllable interfacial order and energetics enable tunable heterojunctions in organic and colloidal quantum dot photovoltaics}, volume={10}, ISSN={2050-7488 2050-7496}, url={http://dx.doi.org/10.1039/D1TA09544G}, DOI={10.1039/d1ta09544g}, abstractNote={Top and bottom surfaces of polymer films are used to construct interfaces in heterojunction based devices, affecting device figure of merit significantly with their different aggregation states.}, number={4}, journal={Journal of Materials Chemistry A}, publisher={Royal Society of Chemistry (RSC)}, author={Zhong, Yufei and Kirmani, Ahmad R. and Lan, Xinzheng and Carpenter, Joshua and Rong-Hui Chew, Annabel and Awartani, Omar and Yu, Liyang and Niazi, Muhammad R. and Voznyy, Oleksandr and Hu, Hanlin and et al.}, year={2022}, pages={1788–1801} }
 @article{carpenter_ghasemi_gann_angunawela_stuard_rech_ritchie_brendan t. o'connor_atkin_you_et al._2019, title={Competition between Exceptionally Long-Range Alkyl Sidechain Ordering and Backbone Ordering in Semiconducting Polymers and Its Impact on Electronic and Optoelectronic Properties}, volume={29}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.201806977}, abstractNote={Abstract}, number={5}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Carpenter, Joshua H. and Ghasemi, Masoud and Gann, Eliot and Angunawela, Indunil and Stuard, Samuel J. and Rech, Jeromy James and Ritchie, Earl and Brendan T. O'Connor and Atkin, Joanna and You, Wei and et al.}, year={2019}, month={Feb} }
 @article{ghasemi_hu_peng_rech_angunawela_carpenter_stuard_wadsworth_mcculloch_you_et al._2019, title={Delineation of Thermodynamic and Kinetic Factors that Control Stability in Non-fullerene Organic Solar Cells}, volume={3}, ISSN={["2542-4351"]}, DOI={10.1016/j.joule.2019.03.020}, abstractNote={Although non-fullerene small molecular acceptors (NF-SMAs) are dominating current research in organic solar cells (OSCs), measurements of thermodynamics drivers and kinetic factors determining their morphological stability are lacking. Here, we delineate and measure such factors in crystallizable NF-SMA blends and discuss four model systems with respect to their meta-stability and degree of vitrification. We determine for the first time the amorphous-amorphous phase diagram in an NF-SMA system and show that its deep quench depth can result in severe burn-in degradation. We estimate the relative phase behavior of four other materials systems. Additionally, we derive room-temperature diffusion coefficients and conclude that the morphology needs to be stabilized by vitrification corresponding to diffusion constants below 10−22 cm2/s. Our results show that to achieve stability via rational molecular design, the thermodynamics, glass transition temperature, diffusion properties, and related structure-function relations need to be more extensively studied and understood.}, number={5}, journal={JOULE}, author={Ghasemi, Masoud and Hu, Huawei and Peng, Zhengxing and Rech, Jeromy James and Angunawela, Indunil and Carpenter, Joshua H. and Stuard, Samuel J. and Wadsworth, Andrew and McCulloch, Iain and You, Wei and et al.}, year={2019}, month={May}, pages={1328–1348} }
 @article{yao_li_hu_chow_chen_zhao_li_carpenter_lai_yang_et al._2018, title={A Facile Method to Fine-Tune Polymer Aggregation Properties and Blend Morphology of Polymer Solar Cells Using Donor Polymers with Randomly Distributed Alkyl Chains}, volume={8}, ISSN={["1614-6840"]}, DOI={10.1002/aenm.201701895}, abstractNote={Abstract}, number={6}, journal={ADVANCED ENERGY MATERIALS}, author={Yao, Huatong and Li, Yunke and Hu, Huawei and Chow, Philip C. Y. and Chen, Shangshang and Zhao, Jingbo and Li, Zhengke and Carpenter, Joshua H. and Lai, Joshua Yuk Lin and Yang, Guofang and et al.}, year={2018}, month={Feb} }
 @article{hu_jiang_chow_ye_zhang_li_carpenter_ade_yan_2018, title={Influence of Donor Polymer on the Molecular Ordering of Small Molecular Acceptors in Nonfullerene Polymer Solar Cells}, volume={8}, ISSN={["1614-6840"]}, url={https://publons.com/wos-op/publon/7528287/}, DOI={10.1002/aenm.201701674}, abstractNote={Abstract}, number={5}, journal={ADVANCED ENERGY MATERIALS}, author={Hu, Huawei and Jiang, Kui and Chow, Philip C. Y. and Ye, Long and Zhang, Guangye and Li, Zhengke and Carpenter, Joshua H. and Ade, Harald and Yan, He}, year={2018}, month={Feb} }
 @article{li_mangalore_zhao_carpenter_yan_ade_yan_muellen_blom_pisula_et al._2018, title={Integrated circuits based on conjugated polymer monolayer}, volume={9}, ISSN={["2041-1723"]}, DOI={10.1038/s41467-017-02805-5}, abstractNote={Abstract}, journal={NATURE COMMUNICATIONS}, author={Li, Mengmeng and Mangalore, Deepthi Kamath and Zhao, Jingbo and Carpenter, Joshua H. and Yan, Hongping and Ade, Harald and Yan, He and Muellen, Klaus and Blom, Paul W. M. and Pisula, Wojciech and et al.}, year={2018}, month={Jan} }
 @article{ye_hu_ghasemi_wang_collins_kim_jiang_carpenter_li_li_et al._2018, title={Quantitative relations between interaction parameter, miscibility and function in organic solar cells}, volume={17}, ISSN={["1476-4660"]}, url={https://doi.org/10.1038/s41563-017-0005-1}, DOI={10.1038/s41563-017-0005-1}, abstractNote={Although it is known that molecular interactions govern morphology formation and purity of mixed domains of conjugated polymer donors and small-molecule acceptors, and thus largely control the achievable performance of organic solar cells, quantifying interaction-function relations has remained elusive. Here, we first determine the temperature-dependent effective amorphous-amorphous interaction parameter, χ aa (T), by mapping out the phase diagram of a model amorphous polymer:fullerene material system. We then establish a quantitative 'constant-kink-saturation' relation between χ aa  and the fill factor in organic solar cells that is verified in detail in a model system and delineated across numerous high- and low-performing materials systems, including fullerene and non-fullerene acceptors. Our experimental and computational data reveal that a high fill factor is obtained only when χ aa  is large enough to lead to strong phase separation. Our work outlines a basis for using various miscibility tests and future simulation methods that will significantly reduce or eliminate trial-and-error approaches to material synthesis and device fabrication of functional semiconducting blends and organic blends in general.}, number={3}, journal={NATURE MATERIALS}, publisher={Springer Nature}, author={Ye, Long and Hu, Huawei and Ghasemi, Masoud and Wang, Tonghui and Collins, Brian A. and Kim, Joo-Hyun and Jiang, Kui and Carpenter, Joshua H. and Li, Hong and Li, Zhengke and et al.}, year={2018}, month={Mar}, pages={253–260} }
 @article{gautam_younts_carpenter_ade_gundogdu_2018, title={The Role of FRET in Non-Fullerene Organic Solar Cells: Implications for Molecular Design}, volume={122}, ISSN={["1089-5639"]}, url={https://doi.org/10.1021/acs.jpca.7b12807}, DOI={10.1021/acs.jpca.7b12807}, abstractNote={Non-fullerene acceptors (NFAs) have been demonstrated to be promising candidates for highly efficient organic photovoltaic (OPV) devices. The tunability of absorption characteristics of NFAs can be used to make OPVs with complementary donor-acceptor absorption to cover a broad range of the solar spectrum. However, both charge transfer from donor to acceptor moieties and energy (energy) transfer from high-bandgap to low-bandgap materials are possible in such structures. Here, we show that when charge transfer and exciton transfer processes are both present, the coexistence of excitons in both domains can cause a loss mechanism. Charge separation of excitons in a low-bandgap material is hindered due to exciton population in the larger bandgap acceptor domains. Our results further show that excitons in low-bandgap material should have a relatively long lifetime compared to the transfer time of excitons from higher bandgap material in order to contribute to the charge separation. These observations provide significant guidance for design and development of new materials in OPV applications.}, number={15}, journal={JOURNAL OF PHYSICAL CHEMISTRY A}, publisher={American Chemical Society (ACS)}, author={Gautam, Bhoj R. and Younts, Robert and Carpenter, Joshua and Ade, Harald and Gundogdu, Kenan}, year={2018}, month={Apr}, pages={3764–3771} }
 @article{zhong_ye_chen_jo_chueh_carpenter_ade_jen_2017, title={A regioregular conjugated polymer for high performance thick-film organic solar cells without processing additive}, volume={5}, ISSN={["2050-7496"]}, url={https://doi.org/10.1039/C7TA02391J}, DOI={10.1039/c7ta02391j}, abstractNote={Regioregular PTB7-Th with pre-designated repeat units achieves over 10% efficiency in thick-film solar cells without the assistance of a solvent additive.}, number={21}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, publisher={Royal Society of Chemistry (RSC)}, author={Zhong, Hongliang and Ye, Long and Chen, Jung-Yao and Jo, Sae Byeok and Chueh, Chu-Chen and Carpenter, Joshua H. and Ade, Harald and Jen, Alex K. -Y.}, year={2017}, month={Jun}, pages={10517–10525} }
 @article{yu_chung_shewmon_ho_carpenter_larrabee_sun_jones_ade_o'connor_et al._2017, title={Flexible inorganic ferroelectric thin films for nonvolatile memory devices}, volume={27}, number={21}, journal={Advanced Functional Materials}, author={Yu, H. and Chung, C. C. and Shewmon, N. and Ho, S. and Carpenter, J. H. and Larrabee, R. and Sun, T. L. and Jones, J. L. and Ade, H. and O'Connor, B. T. and et al.}, year={2017} }
 @article{ye_zhao_li_mukherjee_carpenter_awartani_jiao_hou_ade_2017, title={High-Efficiency Nonfullerene Organic Solar Cells: Critical Factors that Affect Complex Multi-Length Scale Morphology and Device Performance}, volume={7}, ISSN={["1614-6840"]}, url={https://publons.com/wos-op/publon/5290907/}, DOI={10.1002/aenm.201602000}, abstractNote={Organic solar cells (OSCs) made of donor/acceptor bulk‐heterojunction active layers have been of widespread interest in converting sunlight to electricity. Characterizing of the complex morphology at multiple length scales of polymer:nonfullerene small molecular acceptor (SMA) systems remains largely unexplored. Through detailed characterizations (hard/soft X‐ray scattering) of the record‐efficiency polymer:SMA system with a close analog, quantitative morphological parameters are related to the device performance parameters and fundamental morphology–performance relationships that explain why additive use and thermal annealing are needed for optimized performance are established. A linear correlation between the average purity variations at small length scale (≈10 nm) and photovoltaic device characteristics across all processing protocols is observed in ≈12%‐efficiency polymer:SMA systems. In addition, molecular interactions as reflected by the estimated Flory–Huggins interaction parameters are used to provide context of the room temperature morphology results. Comparison with results from annealed devices suggests that the two SMA systems compared show upper and lower critical solution temperature behavior, respectively. The in‐depth understanding of the complex multilength scale nonfullerene OSC morphology may guide the device optimization and new materials development and indicates that thermodynamic properties of materials systems should be studied in more detail to aid in designing optimized protocols efficiently.}, number={7}, journal={ADVANCED ENERGY MATERIALS}, author={Ye, Long and Zhao, Wenchao and Li, Sunsun and Mukherjee, Subhrangsu and Carpenter, Joshua H. and Awartani, Omar and Jiao, Xuechen and Hou, Jianhui and Ade, Harald}, year={2017}, month={Apr} }
 @article{di pietro_erdmann_carpenter_wang_shivhare_formanek_heintze_voit_neher_ade_et al._2017, title={Synthesis of High-Crystallinity DPP Polymers with Balanced Electron and Hole Mobility}, volume={29}, ISSN={["1520-5002"]}, DOI={10.1021/acs.chemmater.7b04423}, abstractNote={We review the Stille coupling synthesis of P(DPP2OD-T) (Poly[[2,5-di(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-3,6-diyl]-alt-[2,2′:5′,2″-terthiophene-5,5″-diyl]]) and show that high-quality, high molecular weight polymer chains are already obtained after as little as 15 min of reaction time. The results of UV–vis spectroscopy, grazing incidence wide-angle X-ray scattering (GIWAXS), and atomic force microscopy show that longer reaction times are unnecessary and do not produce any improvement in film quality. We achieve the best charge transport properties with polymer batches obtained from short reaction times and demonstrate that the catalyst washing step is responsible for the introduction of charge-trapping sites for both holes and electrons. These trap sites decrease the charge injection efficiency, strongly reducing the measured currents. The careful tuning of the synthesis allows us to reduce the reaction time by more than 100 times, achieving a more environmentally friendly, less costly ...}, number={23}, journal={CHEMISTRY OF MATERIALS}, author={Di Pietro, Riccardo and Erdmann, Tim and Carpenter, Joshua H. and Wang, Naixiang and Shivhare, Rishi Ramdas and Formanek, Petr and Heintze, Cornelia and Voit, Brigitte and Neher, Dieter and Ade, Harald and et al.}, year={2017}, month={Dec}, pages={10220–10232} }
 @article{di pietro_nasrallah_carpenter_gann_koelln_thomsen_venkateshvaran_o'hara_sadhanala_chabinyc_et al._2016, title={Coulomb Enhanced Charge Transport in Semicrystalline Polymer Semiconductors}, volume={26}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.201602080}, abstractNote={Polymer semiconductors provide unique possibilities and flexibility in tailoring their optoelectronic properties to match specific application demands. The recent development of semicrystalline polymers with strongly improved charge transport properties forces a review of the current understanding of the charge transport mechanisms and how they relate to the polymer's chemical and structural properties. Here, the charge density dependence of field effect mobility in semicrystalline polymer semiconductors is studied. A simultaneous increase in mobility and its charge density dependence, directly correlated to the increase in average crystallite size of the polymer film, is observed. Further evidence from charge accumulation spectroscopy shows that charges accumulate in the crystalline regions of the polymer film and that the increase in crystallite size affects the average electronic orbitals delocalization. These results clearly point to an effect that is not caused by energetic disorder. It is instead shown that the inclusion of short range coulomb repulsion between charge carriers on nanoscale crystalline domains allows describing the observed mobility dependence in agreement with the structural and optical characterization. The conclusions that are extracted extend beyond pure transistor characterization and can provide new insights into charge carrier transport for regimes and timescales that are relevant to other optoelectronic devices.}, number={44}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Di Pietro, Riccardo and Nasrallah, Iyad and Carpenter, Joshua and Gann, Eliot and Koelln, Lisa Sophie and Thomsen, Lars and Venkateshvaran, Deepak and O'Hara, Kathryn and Sadhanala, Aditya and Chabinyc, Michael and et al.}, year={2016}, month={Nov}, pages={8011–8022} }
 @article{huang_carpenter_li_yu_ade_jen_2016, title={Highly Efficient Organic Solar Cells with Improved Vertical Donor-Acceptor Compositional Gradient Via an Inverted Off-Center Spinning Method}, volume={28}, ISSN={["1521-4095"]}, DOI={10.1002/adma.201504014}, abstractNote={A novel, yet simple solution fabrication technique to address the trade-off between photocurrent and fill factor in thick bulk heterojunction organic solar cells is described. The inverted off-center spinning technique promotes a vertical gradient of the donor-acceptor phase-separated morphology, enabling devices with near 100% internal quantum efficiency and a high power conversion efficiency of 10.95%.}, number={5}, journal={ADVANCED MATERIALS}, author={Huang, Jiang and Carpenter, Joshua H. and Li, Chang-Zhi and Yu, Jun-Sheng and Ade, Harald and Jen, Alex K. -Y.}, year={2016}, month={Feb}, pages={967–974} }
 @article{zhong_wu_li_carpenter_chueh_chen_ade_jen_2016, title={Rigidifying Nonplanar Perylene Diimides by Ring Fusion Toward Geometry-Tunable Acceptors for High-Performance Fullerene-Free Solar Cells}, volume={28}, ISSN={["1521-4095"]}, DOI={10.1002/adma.201504120}, abstractNote={Rigid fused perylene diimide (PDI) dimers bridged with heterocycles exhibit superior photovoltaic performance compared to their unfused semiflexible analogues. Changing the chalcogen atoms in the aromatic bridges gradually increases the twist angles between the two PDI planes, leading to a varied morphology in which the one bridged by thiophene achieves a balance and shows the best efficiency of 6.72%.}, number={5}, journal={ADVANCED MATERIALS}, author={Zhong, Hongliang and Wu, Chen-Hao and Li, Chang-Zhi and Carpenter, Joshua and Chueh, Chu-Chen and Chen, Jung-Yao and Ade, Harald and Jen, Alex K. -Y.}, year={2016}, month={Feb}, pages={951–958} }
 @article{li_lin_jiang_carpenter_li_liu_hu_zhao_ma_ade_et al._2015, title={Dramatic performance enhancement for large bandgap thick-film polymer solar cells introduced by a difluorinated donor unit}, volume={15}, ISSN={["2211-3282"]}, DOI={10.1016/j.nanoen.2015.05.016}, abstractNote={We report a large bandgap (1.9 eV) donor–acceptor copolymer (named PffT2-FTAZ) that enables polymer solar cells with a high power conversion efficiency of 7.8%. An important structural feature of the PffT2-FTAZ polymer is a difluorinated donor unit (3,3′-difluoro-2,2′-bithiophene, or, ffT2) that introduces several surprising and/or beneficial effects. By comparing PffT2-FTAZ with the analog polymer (PT2-FTAZ) without fluorination on the bithiophene donor unit, it is found that the ffT2 unit effectively lowers the HOMO and LUMO energy levels of the polymer and slightly reduces optical bandgap. It also introduces strong interchain aggregation for the polymer in solution, which leads to a highly crystalline polymer film and reasonably high hole transport mobility. On the other hand, the PffT2-FTAZ: fullerene blend still exhibits a reasonably small polymer domain size suitable for polymer solar cell operation. All these positive factors combined leads to dramatically enhanced performance for the polymer solar cells with the power conversion efficiency increasing from 2.8% for PT2-FTAZ to 7.8% for f PffT2-FTAZ. The high PSC performance of PffT2-FTAZ makes it a promising candidate for high efficiency tandem PSCs.}, journal={NANO ENERGY}, author={Li, Zhengke and Lin, Haoran and Jiang, Kui and Carpenter, Joshua and Li, Yunke and Liu, Yuhang and Hu, Huawei and Zhao, Jingbo and Ma, Wei and Ade, Harald and et al.}, year={2015}, month={Jul}, pages={607–615} }
 @article{zhong_li_carpenter_ade_jen_2015, title={Influence of Regio- and Chemoselectivity on the Properties of Fluoro-Substituted Thienothiophene and Benzodithiophene Copolymers}, volume={137}, ISSN={["1520-5126"]}, DOI={10.1021/jacs.5b04209}, abstractNote={By studying the regio- and chemoselectivity of fluoro-substituted thienothiophene and benzodithiophene copolymers, we found polymers made from conventional one-pot polycondensation reaction consist of two distinctly different segments with a ratio of 0.36/0.64. Through further comparative studies of neat regioregular polymers based on each individual segment, we have identified the specific segment that contributes to the superior absorption, packing order, and charge mobility in the corresponding polymers. The unique structure-property relationships are the result of cooperative molecular arrangements of the key segment and noncovalent interaction between the fluoro group and the aromatic proton on the thiophene side-chain of the polymers.}, number={24}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Zhong, Hongliang and Li, Chang-Zhi and Carpenter, Joshua and Ade, Harald and Jen, Alex K. -Y.}, year={2015}, month={Jun}, pages={7616–7619} }
 @article{ma_yang_jiang_carpenter_wu_meng_mcafee_zhao_zhu_wang_et al._2015, title={Influence of processing parameters and molecular weight on the morphology and properties of high-performance PffBT4T-2OD:PC71BM organic solar cells}, volume={5}, DOI={10.1002/aenm.201570126}, abstractNote={The detailed morphology of high efficiency polymer ( PffBT4T-2OD) based organic solar cells is investigated by Wei Ma, Harald Ade, He Yan and co-workers in article number 1501400. It is found that the median domain sizes of PffBT4T-2OD:PC71BM blends processed at different temperatures/ spin rates are nearly identical, while the average domain purity and the molecular orientation relative to polymer:fullerene interfaces can be significantly changed by the processing conditions.}, number={23}, journal={Advanced Energy Materials}, author={Ma, W. and Yang, G. F. and Jiang, K. and Carpenter, J. H. and Wu, Y. and Meng, X. Y. and McAfee, T. and Zhao, J. B. and Zhu, C. H. and Wang, C. and et al.}, year={2015} }
 @article{karpusenko_carpenter_zhou_lim_pan_riehn_2012, title={Fluctuation modes of nanoconfined DNA}, volume={111}, number={2}, journal={Journal of Applied Physics}, author={Karpusenko, A. and Carpenter, J. H. and Zhou, C. D. and Lim, S. F. and Pan, J. H. and Riehn, R.}, year={2012} }
 @article{carpenter_karpusenko_pan_lim_riehn_2011, title={Density fluctuations dispersion relationship for a polymer confined to a nanotube}, volume={98}, number={25}, journal={Applied Physics Letters}, author={Carpenter, J. H. and Karpusenko, A. and Pan, J. H. and Lim, S. F. and Riehn, R.}, year={2011} }